We will continue the studies on the pathogenesis of Creutzfeldt-Jakob disease incorporating in our studies the recent transmission of this disease to hamsters and mice. We expect to complete the studies on viremia. Due to our large animal colony already committed to the above studies only modest preliminary experiments have been possible on fractionation and tissue culture of the agent. These preliminary studies appear promising and we expect to expand fractionation and tissue culture studies as soon as animal space becomes available.